Introduction: The aim of this study was to explore the relationships between TregFoxP3+ cells and Th17 cells and occurrence of lung cancer. Material and methods: The proportions of TregFoxP3+ and Th17 cells, the expression of FoxP3 and RORγt mRNA, and the levels of related cell factors such as transforming growth factor-β (TGF-β), interleukin IL-17 (IL-17) and IL-23 were determined respectively by flow cytometry analysis, real-time-polymerase chain reaction (PCR), and ELISA in peripheral blood of 18 healthy people and 26 patients with non-small cell lung cancer (NSCLC). Results: The levels of TregFoxP3+ and Th17, expression of FoxP3 and RORγt mRNA, and ratios of TregFoxP3+/Th17 and FoxP3/RORγt in peripheral blood with NSCLC were higher than those in healthy controls (p < 0.05). The proportion of Th17 cells from NSCLC patients was positively correlated with that of TregFoxP3+ (r = 0.81, p < 0.05). The receiver-operating characteristic (ROC) curve demonstrates that the increased level of TregFoxP3+/Th17 in the peripheral blood may be a useful indicator in early diagnosis of non-small cell lung carcinoma. The TregFoxP3+/Th17 and FoxP3/RORγt levels for patients in stage IV were higher than those of patients in stages I, II, and III (p < 0.05). The levels of TGF-β, IL-17, and IL-23 were higher in NSCLC patients than those in healthy controls. Conclusions: The results suggest that ratios of Treg/Th17 correlate with the stage of NSCLC.